1. Field of the Invention
The present invention relates to a digital backplane and various methods, systems and devices for controlling a digital backplane, light modulating elements and spatial light modulators.
2. Related Art
The concept of digital LCoS devices has been known for well over 10 years. The U.S. Pat. No. 5,959,598 to McKnight gives an example of many of the basic digital LCoS concepts and is included herein by reference. U.S. Pat. No. 6,650,138 to Zuravleff shows another variation of this “master-slave” mirror drive arrangement. Both of these patents use a feed forward drive method. Both of these patents show a two-storage-bit structure in which one of the storage bits is directly shifted to the next bit for display and thus the two bits of storage are inexorably linked together and connected to a specific output. However, the methods described in these patents require considerable bandwidth.
U.S. Published Patent Application Document No. 2003/0160803 to Willis shows a spatial light modulator microdisplay which uses a “feed forward” drive method. In this application, an N-bit pixel value is compared to a N-bit counter and the result of that comparison is used to drive a display mirror of an LCoS device. Willis shows an N-bit wide comparison occurring 2N times in order to control the bit with each comparison requiring all N-bits. Willis shows needing at least N-bits of memory storage on the display device to affect the PWM control. This means that N-bits must some how be sent/connect to an N-bit wide comparator 2N times in order to control the PWM waveform.